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Four years ago, when Jenni Kluck sought medical help after feeling unusually tired and short of breath, her doctor said she was just fine. She was 26 at the time and appeared perfectly healthy.

“He didn’t even listen to my lungs. He just thought I was being dramatic or too worried,” the Las Vegas mother of two, now 31, recalled Wednesday. When she told him she feared having blood clots, the doctor shrugged off her concern. “He said, ‘Oh, you’ve got to get off Google.’”

After her first doctor dismissed her symptoms, Jenni Kluck went to the emergency room, where doctors found multiple blood clots in her lungs.Jenni Kluck

The next morning, Kluck woke up with severe lung pain and headed to the emergency room, where she was diagnosed with multiple bilateral pulmonary embolisms. That meant she had “multiple blood clots” sprinkled throughout her lungs.

“The doctors in the ER said, ‘Wow, you are a very lucky girl that you came in and went with your gut feeling that something was not right,'" she said.

Hundreds posted their stories on TODAY’s Facebook page urging people to “go with your gut” when it comes to personal health.

“I had pain and other symptoms in my lower abdomen for years my doctor told me it was all in my head. I trusted that doctor but knew my body,” wrote Bonnie Gruver Confer. “I went to a new doctor and he ordered a colonoscopy. He saved my life. I had colon cancer. Second opinions save lives.”

Cheri-lyn Corwin wrote about how one psychologist assumed she was faking her symptoms to divert “attention away from my younger siblings. We finally found a neurologist who gave me a proper diagnosis. I was able to get brain surgery that got me back on my feet.”

Ingrid Pedersen received a second medical opinion that saved her life at age 16. She's now 52.Ingrid Pedersen

Ingrid Pedersen was 16 when she fell ill with symptoms that her doctor attributed to the flu. When she failed to improve, she was sent to the hospital for a chest X-ray. The radiologist diagnosed her with sarcoidosis, a chronic condition that she was told could be treated like diabetes or asthma.

“This was back in 1980, so most people had a lot of faith in their local doctor,” said Pedersen, now 52. “However, my mother, thank goodness, said ‘I’m just not sold on this. I hope you don’t mind, doctor, but I really want to go for a second opinion.”

They went to another doctor, who immediately admitted her into the hospital. She was soon diagnosed with Stage IV Hodgkin’s lymphoma.

“Honestly, if my mom had never gone for that second opinion, if we had put our trust and faith into the doctor and said, ‘Okay, you’re right, we’ll go by what you say,’ I wouldn’t be alive today,” Pedersen said.

From the time she was about 13, Kendra Bradford said she and her mother suspected a thyroid disorder was causing her gland to become increasingly prominent, along with other symptoms typical to hypothyroidism, which ran in the family.

But it wasn’t until more than a decade later after going to a series of doctors that one endocrinologist performed an ultrasound and suggested shrinking her enlarged thyroid with radioactive iodine treatment. Surgery, he told her, was not necessary.

Kendra Bradford's decision to have her thyroid removed led doctors to discover cancer.Courtesy of Kendra Bradford

“I said, I don’t care, I want you to take my thyroid out. There’s something just not right,” she recalled. She went in for surgery three months later.

“I remember waking up from surgery. I looked at my mom and said, What’s wrong? Do I have cancer or something? And she said yes.”

The cancer had already spread to her lymph nodes by then. After eight years of treatment, she is now cancer free at 35.

“Always, always, always advocate for yourself. My gut always said there was something wrong, but I was naïve and young and I didn’t realize you could go and get a second opinion,” Bradford said. “I didn’t know that it was okay to ask.”

Pedersen, now 52 and living “a very productive life,” agreed.

“There are times you just have a weird feeling. You know you’re body. You know when something just doesn’t feel right. The doctor won’t know how you feel inside,” she said.

Pedersen said she was glad to see someone like Wilson go public with her experience.

“What’s great is when the stars or these celebrities tell their stories, it makes other people listen. It gets out in the public,” she said. “If it’s an everyday person, you might not listen as much as when a Rita Wilson or Angelina Jolie says something. When they speak, you say, ‘Wow’ and pay attention.”